Cephalometrics

CephalometricsCephalometrics
Utkarsh
www.indiandentalacademy.comwww.indiandentalacademy.com

• Introduction
• Uses and advantages of cephalogram
• Limitations of cephalometrics
• Cephalostat
• Obtaining the cephalogram
• Cephalometric landmarks
• Cephalometric tracing
• Cephalometric analysis
ContentsContents

CephalometricsCephalometrics
• Defn
: cephalometrics is a specialized radiographic
technique for obtaining various measurements of head
• The basic elements used in geometric analysis of
cephalograms are curves, landmark points and lines.
Ceph=headCeph=head
metrics=measuremetrics=measure

• Cephalometric analysis is a collection of
numbers to compress information from the
cephalogram for clinical use.
• Different analysis are required for different
purposes.

Uses and advantagesUses and advantages
• Patient education and convincing.
• Important diagnostic aid.
• Helps in classifying dental and skeletal
abnormalities as well as establishing facial type.
• Helps in treatment planning and treatment
progress

• Helps in prediction of growth related changes
and that associated with surgical treatment.
• Helps in study of craniofacial morphology in
various populations.
• It is a valuable aid in research of craniofacial
region.
• Aids in medico-legal cases

Problems and limitationsProblems and limitations
• It is a two dimensional representative of three
dimensional structures.
• Problems in orientation of patient while procuring
radiograph.
• Problems of magnification and blurring
• Processing errors
• Difficulty in location of landmarks precisely.
• Mean population averages differ from characteristics of a
particular patient.
• Use of chronological age for comparisons and
references within age classes instead of skeletal
• Radiation hazards

TYPES OF CEPHALOGRAMS
• Can be of two types
1. Lateral cephalogram: This provides
lateral view of the skull
2. Frontal cephalogram: This provides
antero-posterior view of the skull

Lateral and frontal cephalogramLateral and frontal cephalogram

5 feet
X-ray source
Cephalostat
Film

Cephalometric equipment
• Consists of an X-ray source and a head holding device
called cephalostat
• Cephalostat consists of two ear rods that prevent
movement of the head in horizontal plane
• Vertical stabilization is provided by an orbital pointer that
contacts the lower border of the left orbit
• The upper part of the face is supported by a forehead
clamp positioned above the region of the nasal bridge

• The distance between X-ray source and the mid-sagittal plane of
the patient is fixed at 5 feet (152.4 cm)
• Thus the equipment helps in standardization using a constant head
position which helps to compare serial radiographs
• Natural Head Position (NHP) is a standardized and reproducible
orientation of the head in space when one is focusing on a distant
point at eye level.

Cephalometric landmarksCephalometric landmarks
Types
– Anatomic
– Derived
 Hard tissue landmarks
 Soft tissue landmarks
Anatomic
These landmarks represent actual anatomic landmarks of the skull.
Derived landmarks
These are obtained secondarily from anatomic landmarks.

Criteria for landmark selection
• Should be easily identifiable
• Should be uniform in outline and
reproducible
• Should permit valid quantitative
measurements of lines and angles
projected from them.

Anatomical structures
• The major bony structures are:
• Sphenoid bone
• Zygomatic bones
• Maxilla
• Mandible

Unilateral landmarks
in lateral cephalograms
• Nasion (Na)- frontonasal
suture at its most superior
point on the curve at the
bridge of nose
• Anterior nasal spine
(ANS)-the most anterior
point on the maxilla at the
level of the palate
• Subspinale(“A” point)-
the most posterior point on
the curve between ANS
and superior Prosthion

• Supramentale (“B” point)-
The most posterior point of
the bony curvature of the
mandible below
Infradentale and above
Pogonion .
• Pogonion (Pog)-the most
anterior point on the
contour of the chin
• Gnathion (Gn)-The most
anterior inferior point on
the lateral shadow of the
chin
• Menton (Me)-The lowest
point on the symphyseal
outline of the chin

• Basion (Ba)-The most inferior
posterior point in the sagital
plane on the anterior rim of the
foramen magnum
• Posterior nasal spine (PNS)-
The most posterior point on
the bony hard palate in the
sagital plane
• Sella (S)-The center of the
hypophyseal fossa
• Broadbent registration point:It
is the midpoint of the
perpendicular from the center
of sella tursica to Bolton’s
plane

Bilateral landmarks
Following are the points-
• Orbitale (Or)-The lowest point of
the bony orbit. Usually the
lowest point on the averaged
outline is used for
construction of Frankfurt
Plane
• Gonion (Go)-The most posterior
inferior point at the angle of the
mandible.
• Pterygomaxillary fissure (PTM)-
Bilateral tear-drop shaped area of
w of which is the posterior
surfaces of the maxillary
tuberosities

Cephalometric
Lines (Planes)
• Horizontal
• Vertical
Horizontal planes:
• S-N plane :It is the cranial
line between center of sella
and the nasion

• Frankfurt horizontal plane
:The common tangent to the
upper external auditory meatus
(at porion) and the inferior
border of the orbit (orbitale)

• Functional occlusal line
(FOL):A line averaging the
points of posterior occlusal
contacts from first permanent
molars to the primary molars or
bicuspids

• Mandibular plane :
A line connecting gonion
and menton(Downs)

• Palatal plane: A line joining
ANS and PNS

Vertical planes
• A-Pog line :Line from
Point A to pogonion
Pog
A

• Facial plane :Line
from nasion to
pogonion
N
Pog

DOWN'SANALYSIS

• One of the most commonly used analysis
• Downs based his findings on 20
Caucasian individuals of 12-17 years age
group of both sexes
• Downs analysis consists of 10 parameters
-5 skeletal and five dental

Mean Reading : 87.5o
Range : 82o
– 95o
N
Pog
Po
Or
Skeletal parameters
1. Facial angle: It is the
angle formed by the
intersection of nasion-
pogonion plane and the
FH plane
This angle gives us an
indication of the antero-
posterior positioning of
the mandible in relation
to the cranium. This
value increases in cases
of skeletal CL III while it
decreases in CL II caseswww.indiandentalacademy.comwww.indiandentalacademy.com

Mean Reading : 0o
Range : -8.5o
– 10o
Angle of convexity: this is
formed between the
intersection of a line from
nasion to Point A ,and a line
from Point A to pogonion
This angle reveals the
convexity or concavity of the
skeletal profile
A positive angle or an
increased angle shows a
prominent maxillary base
compared to mandible or a
retrognathic profile,while a
negative or decreased angle
shows a prognathic profile
N
A
Pog

Mean Reading : -4.6o
Range : 0o
– - 9o
A-B Plane: this angle is
formed between a line
connecting Point A and
Point B , and a line joining
nasion to pogonion.
This angle is indicative of
the maxillo-mandibular
relationship in relation to
the facial plane
It is usually negative as
Point B is Positioned
behind Point A
In cases of CL III
malocclusions , a positive
angle is seen
N
A
Pog
B

Range : 17o
– 28o
Formed by intersection
of mandibular plane
with FH Plane.
An increased plane is
suggestive of a vertical
grower with a
hyperdivergent facial
pattern
Po
Or
Go
Me

Range : 53o
– 66o
This angle is formed
by joining sella-
gnathion line with FH
plane . This angle is
larger in CL II patterns
than CL III patterns.It
indicates the growth
pattern of the
individual.If the angle is
greater than normal, it
indicates greater
vertical growth of the
mandible and if it is
lesser ,it indicates
horizontal growth of the
mandible
Po
Or
Go
Se

Mean Reading : 9.3o
Range : 1.5o
– 1.4o
..
between occlusal
plane and F.H. plane.
Downs constructed the
occlusal plane by
bisecting the occlusion
of first permanent
molars and incisor
overbite. This angle
gives us a measure of
the slope of occlusal
plane relative to F.H.
plane
Po
Or
OP

Mean reading : 135.4o
Range : 130o
– 150o
between the long
axes of upper and
lower incisors. This
angle decreases in CL
I bimax.protrusion and
CL II DivI.cases
,whereas it increases
in CL II DivII cases

OP

Mean reading : 1.4o
Range : -8.5o
– 7o
by intersection of
long axis of lower
incisor and
mandibular plane.
An increase in this
angle is indicative of
lower incisor
proclination
Go
Me

This is a linear
measurement between
incisal edge of maxillary
central incisor and a line
joining Point A to pogonion
Average value is 2.7mm
and range is -1 to 5mm
It is more in patients with
upper incisor proclination
A
Pog

Vorhies and Adams (1951)
Wriggle

STEINER’SANALYSIS

• Developed in 1930 by Cecil C. Steiner
• This analysis aims at providing maximal
clinical information with the least number
of measurements

STEINER’S ANALYSIS
SKELETAL ANALYSIS
DENTAL ANALYSIS
SOFT TISSUE ANALYSIS

Mean reading : 82o
It is the angle
formed by the intersection
of S.N. plane and a line
joining nasion and point A
This angle indicates
the relative antero-
posterior positioning of
maxilla in relation to
cranial base
A larger than
normal value indicates a
prognathic maxilla while
a smaller value suggests a
retrognathic maxilla
N
A
Se

Mean reading : 80o
It is the angle
between S.N. plane
and a line joining
nasion to Point B.
This angle indicates
the antero-posterior
positioning of the
mandible in relation to
cranial base
An increase indicates
a prognathic mandible
and lesser value
suggests retrusive
mandible
N
Se
B

ANB
Mean reading : 2o
This angle is formed by
intersection of the lines
joining nasion to Point
A, and nasion to Point
B. It denotes the
relative position of
maxilla and mandible to
each other. An increase
is suggestive of CLII
skeletal tendency while
lesser than normal
suggests CLIII skeletal
relationship

Mean reading : 14o
Formed between
occlusal plane and
S.N. plane .The
occlusal plane is
represented by a line
passing between the
overlapping cusps of
first premolars and
first molars. This
angle denotes the
relation of occlusal
plane to cranium and
face.
N
Se
OP

Mean reading : 32o
It is the angle formed between
Mandibular plane and S.N.
plane. The mandibular plane is
a line connecting gonion and
gnathion
This angle indicates growth
pattern;a lower angle suggests
a horizontal growing face and
increased angle shows a
vertical pattern
N
Se
Go
Gn

Upper incisor to N-A(angle)-
Formed by intersection of long
axis of upper centrals and line
joining nasion to point A.
It indicates the relative inclination
of upper incisors; increased angle
is seen during proclination
Upper incisor to N.A (Linear)-
It is a linear measurement formed
between labial surface of upper
central incisor and a line joining
nasion to Point A .
This value helps in determining
upper incisor position ;it increases
in proclined upper incisors

Lower incisor to N.B (angle)-
Formed between N-B plane and
long axis of lower incisor
It shows us the inclination of
lower central incisor; an increased
value shows proclined incisor and
decreased angle gives retroclined
incisor
Lower incisor to N.B (Linear)-
It is the linear distance between
Labial surface of lower central
incisor and a line joining nasion to
Point B.
It helps us to assess lower
incisor inclination; increased value
shows proclination and vice-versa

Mean reading : 130o
Interincisal angle-Formed between
long axis of upper central and long
axis of lower central incisors.
A decreased angle is seen in
proclination of incisors and
increased in retroclined incisors

Pog’
Soft tissue analysis
S-line – Steiner suggests
that in a well balanced face
the lips should touch a line
extending from soft tissue
contour of the chin to the
middle of an ‘S’ formed by
lower border of nose
If lips are beyond this line , it
indicates protrusive lips and
convex profile;and if behind
the line shows retrusive lips
and the patient may have
concave profile

TWEED’SANALYSIS

TWEED’S ANALYSIS
• Three planes are used forming a
diagnostic triangle:
1)Franfurt horizontal plane (FH PLANE)
2)Mandibular plane(MP)
3)Long axis of mandibular incisor(MIA)
• Frankfort mandibular plane angle :
formed by intersection of FH plane
with mandibular plane (mean=25°)

SOFT TISSUE NASION
PRONASALE
SUB NASALE
SUB SPINALE
LABRALE SUPERIUS
STOMION
LABRALE INFERIUS
SUB MENTALE
SOFT TISSUE POGONION
SKIN GNATHION
SOFT TISSUE CEPHALOMETRIC LANDMARKS

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